1. Field of the Invention
The present invention relates to products made or derived from tobacco, or that otherwise incorporate tobacco, and are intended for human consumption. In particular, embodiments of the present invention relate to apparatuses for refining tobacco material used in a smoking article, such as a cigarette.
2. Description of Related Art
Smoking articles, such as cigarettes, typically have a substantially cylindrical structure and include a charge, roll or column of smokable material such as shredded tobacco surrounded by a paper wrapper, thereby forming a tobacco rod.
The roll or column of tobacco used to fill the tobacco rod used in the manufacture of cigarettes may be cut from reconstituted tobacco sheet (such as, for example, R.J. Reynolds Tobacco Company so-called G-7 reconstituted tobacco sheet). Representative methods for making certain types of reconstituted tobacco sheet using papermaking-type processes are set forth, for example, in U.S. Pat. No. 3,847,164 to Mattina; U.S. Pat. No. 4,131,117 to Kite et al.; U.S. Pat. No. 4,182,349 to Selke; U.S. Pat. No. 4,308,877 to Mattina; U.S. Pat. No. 4,341,228 to Keritsis; U.S. Pat. No. 4,421,126 to Gellatly; U.S. Pat. No. 4,706,692 to Gellatly; U.S. Pat. No. 4,941,484 to Clapp et al.; U.S. Pat. No. 4,962,774 to Thomasson et al.; U.S. Pat. No. 4,987,906 to Young et al.; U.S. Pat. No. 5,056,537 to Brown et al.; U.S. Pat. No. 5,143,097 to Sohn et al.; U.S. Pat. No. 5,322,076 to Brinkley et al.; U.S. Pat. No. 5,325,877 to Young et al.; U.S. Pat. No. 5,377,698 to Litzinger; U.S. Pat. No. 5,445,169 to Brinkley et al.; U.S. Pat. No. 5,501,237 to Young et al.; and U.S. Pat. No. 5,533,530 to Young et al.; which are incorporated herein by reference.
In the manufacture of cigarettes, tobacco leaf is processed to separate the stems from the lamina. The lamina are shredded and formed into cigarettes or other smoking articles. The stems are not successfully utilizable as such in cigarette making because of their relatively large diameter, their hard nature and poor burning properties. Nevertheless, tobacco stem material constitutes a substantial proportion of the leaf, usually about 20 to 25% of the weight thereof, and contains other materials common to the lamina. In the past, therefore, efforts have been made to process the stem material for use in smoking articles. In this regard, specifically designed machinery has been employed for the treatment and/or processing of tobacco leaf stem material so as to form a tobacco pulp material, which can be formed into a sheet material and cut to an appropriate length. In one representative process, the tobacco sheet, once formed from the tobacco pulp material, is then dried to about 12% moisture and has a temperature slightly greater than ambient before being directed to a downstream slitter device for slitting the sheet into ribbons of various widths such as, for example, on the order of about 1-3 inches wide. Typically, the tobacco leaf stem material may be refined into the tobacco pulp material using a refiner, such as a Series 4000 double disc refiner available from Beloit Corporation (Metso Paper, Inc.). Types of equipment and methodologies suitable for the processing of tobacco leaf stem material also are set forth, for example, in U.S. Pat. No. 3,204,641 to Jones; U.S. Pat. No. 3,411,514 to Hind et al.; U.S. Pat. No. 3,556,112 to dela Burde et al.; U.S. Pat. No. 3,690,328 to Quarenghi; U.S. Pat. No. 4,167,191 to Jewell et al.; U.S. Pat. No. 4,195,646 to Kite; U.S. Pat. No. 4,300,579 to Ulrich; and U.S. Pat. No. 4,386,617 to Brackmann et al.; which are incorporated herein by reference.
Generally, double disc refiners implement a pair of rotatable discs with disc blades or other refining arrangements disposed thereon. The rotatable discs rotate against respective stationary blade arrangements or other refining arrangements, for grinding or otherwise refining the tobacco material supplied therebetween. The rotatable discs are coupled to a drive shaft driven by a drive motor. The rotational forces (torque) associated with the coupling to the drive shaft, and friction associated with the refining process and material processed thereby, for example, may cause portions of the rotatable discs and/or the disc blades to wear. Such wear issues typically lead to downtime associated with the refiner machine to allow for repairs, which can be costly and time consuming. Furthermore, the cost to replace the rotatable discs, stationary refining arrangements, and other components associated therewith, after such components succumbing to wear issues, can be substantial.
As such, it would be desirable to provide refining machinery capable of better withstanding various wear issues associated with the refining process performed thereby, so as to reduce instances of downtime for repairing such machinery, and also reducing costs associated with replacing components thereof.